The Macaca fascicularis monkey has been developed by us in the past as an experimental model for the study of obstructive atherosclerosis of the coronary and peripheral arteries, with the coronary artery lesions being located in the proximal epicardial arteries leading to myocardial ischemia as indicated by EKG and myocardial necroses and fibroses. Recently, we developed this species as a model for the study of suppression of dietary induced coronary atherosclerotic heart disease (CAHD) and generalized atherosclerosis by exercise. A research plan is proposed to utilize this model to test the effect of controlled vigorous conditioning exercise on the biochemical and morphological fate of already established experimental atherosclerosis and CAHD by (1) placing monkeys on an atherogenic (high butter-high cholesterol) diet for 24 months, followed by continuation of that diet plus exercise for 18 more months; (2) placing monkeys on the same regimen without exercise; (3) feeding monkeys the atherogenic diet alone for 24 months; (4) feeding monkeys the control diet alone for 42 months. Serial evaluations will be made on changes in the luminal diameter of coronary and peripheral arteries by in vivo angiography and on the effect of these changes on the function of the myocardium (including EKG by radiotelemetry). The EKG and angiographic findings will be correlated to serum lipids and lipoproteins. These in vivo findings then will be correlated to the post-mortem findings of the morphological and biochemical composition of heart and arteries, especially with regard to arterial lipids, connective tissue and calcium. The data of animals from all experimental groups will be compared. The proposed studies may help to clarify whether exercise is capable of reversing, arresting or at least ameliorating established CAHD and generalized atherosclerosis even though the atherogenic diet is continued.